<!DOCTYPE html>
<html>
	<head>
		<style>
			.dropbtn {
				background-color: black;
				color: white;
				padding: #px;
				font-size: #px;
				border: none;
			}
			.dropdown {
				position: relative;
				display: inline-block;
			}
			.dropdown-content {
				display: none;
				position: absolute;
				background-color: lightgrey;
				min-width: #px;
				z-index: 1;
			}
			.dropdown-content a {
				color: black;
				padding: #px #px;
				text-decoration: none;
				display: block;
			}
			.dropdown-content a:hover {
				background-color: white;
			}
			.dropdown:hover .dropdown-content {
				display: block;
			}
			.dropdown:hover .dropbtn {
				background-color: grey;
			}
		</style>
	</head>
	<body>
		<div class="dropdown">
			<button class="dropbtn">下拉列表</button>
			<div class="dropdown-content">
				<a href="http://www.php.cn/">1</a>
				<a href="http://www.php.cn/">2</a>
				<a href="http://www.php.cn/">3</a>
			</div>
		</div>
	</body>

</html>